Concept: The torsion equation is given by: $\frac{T}{J} = \frac{τ }{R} = \frac{{G\theta }}{L}$ Where, T is the torque applied, J = polar moment of inertia, τ = shear strength of material, G = modulus of rigidity, θ = angular deflection of shaft (in radians). $\frac{T}{J} = \frac{τ }{r}$ $T = \frac{\tau J}{r} =\frac{\tau}{r} \times \frac{\pi d^4}{32}=\frac{\pi \tau d^3}{16}$ Calculation: τ = 48 N/cm2, d = 3 cm $T =\frac{\pi \tau d^3}{16}=\frac{\pi \times 48 \times3^3}{16}=81\pi~Ncm$